Buggy code:
public class Form < T > extends WebMarkupContainer implements IHeaderContributor , IFormSubmitListener { private static final String HIDDEN_DIV_START = "<div<seq2seq4repair_space>style=\"width:0px;height:0px;position:absolute;left:-100px;top:-100px;overflow:hidden\">" ; public abstract static class ValidationVisitor implements IVisitor < FormComponent < ? > , Void > { public void component ( final FormComponent < ? > formComponent , final IVisit < Void > visit ) { } public abstract void validate ( FormComponent < ? > formComponent ) { } } private static class FormModelUpdateVisitor implements IVisitor < Component , Void > { private final Form < ? > formFilter ; public FormModelUpdateVisitor ( Form < ? > formFilter ) { } public void component ( final Component component , final IVisit < Void > visit ) { } } public static final String METHOD_GET = "get" ; public static final String METHOD_POST = "post" ; private static final short FLAG_SUBMITTED = FLAG_RESERVED1 ; private static final Logger log = LoggerFactory . getLogger ( Form . class ) ; private static final long serialVersionUID = 1L ; private static final String UPLOAD_FAILED_RESOURCE_KEY = "uploadFailed" ; private static final String UPLOAD_TOO_LARGE_RESOURCE_KEY = "uploadTooLarge" ; private IFormSubmittingComponent defaultSubmittingComponent ; private Object formValidators = null ; private Bytes maxSize = null ; private short multiPart = 0 ; private static final short MULTIPART_HARD = 1 ; private static final short MULTIPART_HINT = 2 ; public Form ( final String id ) { } public Form ( final String id , IModel < T > model ) { } public void add ( IFormValidator validator ) { } public void remove ( IFormValidator validator ) { } private final int formValidators_indexOf ( IFormValidator validator ) { } private final IFormValidator formValidators_remove ( IFormValidator validator ) { } private final IFormValidator formValidators_remove ( int index ) { } public final void clearInput ( ) { } public final void error ( String error , Map < String , Object > args ) { } public final IFormSubmittingComponent findSubmittingButton ( ) { } public final IFormSubmittingComponent getDefaultButton ( ) { } public final Collection < IFormValidator > getFormValidators ( ) { } public final CharSequence getJsForInterfaceUrl ( CharSequence url ) { } public Bytes getMaxSize ( ) { } public Form < ? > getRootForm ( ) { } public String getValidatorKeyPrefix ( ) { } public final boolean hasError ( ) { } public boolean isRootForm ( ) { } public final boolean isSubmitted ( ) { } @ Override public boolean isVersioned ( ) { } public final void onFormSubmitted ( ) { } public void process ( IFormSubmittingComponent submittingComponent ) { } private boolean process ( ) { } private void callOnError ( ) { } private void markFormsSubmitted ( ) { } public final void setDefaultButton ( IFormSubmittingComponent submittingComponent ) { } public void setMaxSize ( final Bytes maxSize ) { } public void setMultiPart ( boolean multiPart ) { } @ Override public final Component setVersioned ( final boolean isVersioned ) { } public final < R > R visitFormComponents ( final IVisitor < ? extends FormComponent < ? > , R > visitor ) { } public final < R > R visitFormComponentsPostOrder ( final IVisitor < ? extends FormComponent < ? > , R > visitor ) { } private boolean anyFormComponentError ( ) { } private void dispatchEvent ( final Page page , final String url ) { } private void formValidators_add ( final IFormValidator validator ) { } private IFormValidator formValidators_get ( int index ) { } private int formValidators_size ( ) { } private void inputChanged ( ) { } protected void appendDefaultButtonField ( final MarkupStream markupStream , final ComponentTag openTag ) { } protected void beforeUpdateFormComponentModels ( ) { } protected void delegateSubmit ( IFormSubmittingComponent submittingComponent ) { Form < ? > formToProcess = this ; if ( submittingComponent != null ) { formToProcess = submittingComponent . getForm ( ) ; submittingComponent . onSubmit ( ) ; } <START_BUG> Visits . visitComponentsPostOrder ( this , new IVisitor < Form < ? > , Void > ( ) { <END_BUG> public void component ( Form < ? > form , IVisit < Void > visit ) { if ( ( form . isEnabledInHierarchy ( ) ) && ( form . isVisibleInHierarchy ( ) ) ) { form . onSubmit ( ) ; } } } , new ClassVisitFilter ( Form . class ) ) ; } public final String getHiddenFieldId ( ) { } protected String getMethod ( ) { } @ Override protected boolean getStatelessHint ( ) { } private boolean isMultiPart ( ) { } protected boolean handleMultiPart ( ) { } protected void onFileUploadException ( final FileUploadException e , final Map < String , Object > model ) { } @ Override protected void internalOnModelChanged ( ) { } protected final void markFormComponentsInvalid ( ) { } protected final void markFormComponentsValid ( ) { } private void markNestedFormComponentsValid ( ) { } private void internalMarkFormComponentsValid ( ) { } @ Override protected void onComponentTag ( final ComponentTag tag ) { } @ Override protected void renderPlaceholderTag ( ComponentTag tag , Response response ) { } protected boolean encodeUrlInHiddenFields ( ) { } @ Override protected void onComponentTagBody ( final MarkupStream markupStream , final ComponentTag openTag ) { } protected void writeParamsAsHiddenFields ( String [ ] params , AppendingStringBuffer buffer ) { } private String recode ( String s ) { } @ Override protected void onDetach ( ) { } protected void onError ( ) { } @ Override protected void onBeforeRender ( ) { } protected void onSubmit ( ) { } protected final void updateFormComponentModels ( ) { } private final void updateNestedFormComponentModels ( ) { } private void internalUpdateFormComponentModels ( ) { } protected final void validate ( ) { } protected void onValidate ( ) { } protected final void validateComponents ( ) { } private boolean isFormComponentVisibleInPage ( FormComponent < ? > fc ) { } protected final void validateFormValidator ( final IFormValidator validator ) { }

Fix:
Visits . visitPostOrder ( this , new IVisitor < Form < ? > , Void > ( ) {